A variety of polypeptide cytokines, hormones and immune system modulators have been used to stimulate production and activity of bone marrow-derived cells. However, little progress has been made in obtaining the same physiologic activities in culture and in vivo using simple, chemically synthesized small molecules. For example, there are relatively few reports of the use of simple, small molecules in stimulating production and function of various blood components, including, without limitation, red blood cells (RBCs) and white blood cells (WBCs), in stimulating the response to vaccinations, in enhancing differentiation and in the nontoxic treatment of neoplasia. The present invention relates to such methods, as well as others, and to compounds suitable for use in same.